"Oh Jesus Christ, stupid questions", said Collins, with the committee chair Labour's Deborah Russell chipping in calling it "a white girl comment - crikey".
"Oh no", shot back Collins,"it's actually someone who is utterly sick of being demonised for my ethnicity thank you very much."
Coffey protested saying he wasn't even talking about her and apologised to the submitter.
"Is he apologising for Deborah's comment or for his?" interjected ACTs David Seymour.
"No need to apologise for me - how patronising - I can apologise for myself and I have no intention of [doing that]," Collins said.
Meanwhile National's leadership continues to deal with the fallout, with Muller facing more questions today.
He's repeatedly talked about Shane Reti, number 17, as a valued member of the caucus and an up-and-coming MP.
Reti was targeted by Labour's Māori caucus co-chair and Government minister Willie Jackson in the House after the National MP asked a question about employment programmes.
"Māori, ethnic communities, Pasifika and disability groups ... those are the people we'll continue to fight for and shame on that member for not standing up for his people!"
Dan Bidois - ranked at number 46 - has also been cited by Muller as a talented Māori member of the caucus, and one with an important portfolio responsibility, Workplace Relations and Safety.
He told RNZ he "fully rejected identity based politics", and the "notion that we have to have a certain amount of ethnicity, or particular type of Māori".
New Zealanders wanted a government that would deliver for them, to improve the economy and get the country "out of this mess", said Bidois.
Muller also received support today from an unexpected quarter - ousted deputy leader Paula Bennett.
- RNZ